Liquid crystal display device
A liquid crystal display device mainly includes a first substrate having a light-shielding matrix formed thereon, a second substrate, and a liquid crystal layer sandwiched between the first and the second substrates. The first substrate is attached to the second substrate by a light-cured sealant. The present invention is characterized in that the light-shielding matrix has at least one transparent area located at a position facing the interface between the light-cured sealant and the liquid crystal layer thereby allowing a radiation entering the liquid crystal display device from the first substrate to reach the light-cured sealant through the at least one transparent area of the light-shielding matrix.
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1. Field of the Invention
The present invention relates to a liquid crystal display (LCD) device, and more particularly to a liquid crystal display device using a light-cured sealant.
2. Description of the Related Art
First, a conventional liquid crystal display device 100 will be described with reference to
Referring to
Referring to
The light-shielding matrix 122 is made of a light-blocking material or a light-absorbing material for absorbing external light and improving the contrast of a displayed image. As shown in
Therefore, when a UV curable sealant is used to seal the liquid crystal display device 100, since a portion of the sealant 107 is (especially the interface between the liquid crystal layer 106 and the sealant 107) covered by the light-shielding matrix 122, the UV light is unable to reach the covered portion of the sealant 107 thereby resulting in incomplete curing thereof. Therefore, that uncured sealant will react with the liquid crystal layer and cause the latter to degrade in its performance as a liquid crystal material.
In the field of flat panel display, the two substrates may be affixed to each other with a thermosetting sealant. However, this method needs a relatively high curing temperature which the liquid crystal cannot tolerate, and therefore the step of curing the thermosetting sealant should be conducted prior to filling of the liquid crystal material.
However, in a newly proposed technique based on a one drop fill (abbreviated ODF) method disclosed in U.S. Pat. No. 5,263,888 to Ishihara et al., one of the substrates receives droplets of liquid crystal material prior to joining it with the other substrate. This greatly reduces the number of the manufacturing steps and increases the manufacturing efficiency. However, since the liquid crystal material is dropped prior to the step of sealing the two substrates, this method cannot use the thermal setting sealant but must use the UV curable sealant instead.
Therefore, in order to ensure that the UV curable sealant can be cured completely thereby preventing it from reacting with the liquid crystal material, the light-shielding matrix that blocks the sealant from light must be kept away from the sealant. But this means the redundant area outside the display region of liquid crystal panel will increase or the area of the display region will decrease if the area of the liquid crystal panel remains the same, either the former design or the latter design varies from the developing trend of the liquid crystal display device.
The present invention therefore seeks to provide a liquid crystal display device that overcomes or at least reduces the above-mentioned problems of the prior art.
SUMMARY OF THE INVENTIONIt is an object of the invention to provide a liquid crystal display device which prevent deleterious mixing of the liquid crystal material with any potentially uncured sealants.
The liquid crystal display device according to a general aspect of the present invention mainly comprises a first substrate, a second substrate and a liquid crystal layer sandwiched between the first and the second substrates. The first substrate is attached to the second substrate by a light-cured sealant (e.g. a UV cured sealant). The first substrate has a light-shielding matrix (e.g. a black matrix). The present invention is characterized in that the light-shielding matrix has at least one transparent area located at a position facing the interface between the light-cured sealant and the liquid crystal layer thereby allowing a radiation that enters the liquid crystal display device from the first substrate to reach the light-cured sealant through the at least one transparent area of the light-shielding matrix. Since the sealant located around the interface is cured completely, even there is any other uncured sealant within the sealant, such uncured sealant will be kept from reacting with the liquid crystal material thereby assuring the performance of the liquid crystal material.
According to one embodiment of the present invention, the transparent area of the light-shielding matrix comprises a slit extending along the interface between the light-cured sealant and the liquid crystal layer.
According to another embodiment of the present invention, the transparent area of the light-shielding matrix has a saw-toothed outline
According to a further embodiment of the present invention, the light-shielding matrix has a plurality of transparent areas arranged in a plurality of parallel columns wherein at least one column of the transparent areas is formed along the interface between the light-cured sealant and the liquid crystal layer. Preferably, the transparent areas in adjacent columns are arranged in a staggered configuration.
However, when the liquid crystal display device is in use, the light generated from the backlight will pass through the transparent area(s) of the light-shielding matrix thereby deteriorating the performance (for example, lower the contrast ratio) of the light-shielding matrix. Therefore, the present invention provides two solutions: 1) using a normally black mode liquid crystal display device comprising a pair of polarizers attached on the first and the second substrates respectively in a manner that the polarizers cover areas on the first and the second substrates facing the transparent area of the light-shielding matrix; and 2) forming an opaque pattern on the second substrate at a position corresponding to the transparent area of the light-shielding matrix.
The aformentioned opaque pattern preferably comprises an anti-reflection surface layer facing the first substrate in order to prevent the light scattered by the light-shielding matrix from being reflected from the opaque pattern to pass through the transparent area of the light-shielding matrix. The anti-reflection surface layer may be an oxidized metal film or may be formed of a refractory metal (e.g., Cr, Ta, Mo or Ti).
Other objects, advantages, and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.
The present invention is characterized in that the light-shielding matrix 210 has a transparent area 214 of the light-shielding matrix 210 formed at a position facing the interface 216 thereby allowing the sealant located around the interface 216 between the light-cured sealant 208 and the liquid crystal layer 206 to be cured completely. Since the sealant located around the interface 216 is cured completely, even there is any other uncured sealant within the sealant 208, such uncured sealant will be kept from reacting with the liquid crystal material thereby assuring the performance of the liquid crystal material.
Furthermore,
Although the invention has been explained in relation to its preferred embodiment, it is to be understood that many other possible modifications and variations can be made without departing from the spirit and scope of the invention as hereinafter claimed.
Claims
1. A liquid crystal display device, comprising:
- a first substrate;
- a second substrate;
- a liquid crystal layer sandwiched between the first and the second substrates;
- a light-cured sealant for attaching the first substrate to the second substrate; and
- a light-shielding matrix formed on the first substrate,
- wherein the light-shielding matrix includes a slit extending along the interface between the light-cured sealant and the liquid crystal layer thereby allowing a radiation entering the liquid crystal display device from the first substrate to reach the light-cured sealant through slit, wherein the slit overlaps with only a portion of the light-cured sealant and exposes the interface between the light-cured sealant and the liquid crystal layer.
2. The liquid crystal display device as claimed in claim 1, wherein the second substrate further comprises an opaque pattern formed at a position facing the slit.
3. The liquid crystal display device as claimed in claim 2, wherein the opaque pattern comprises an anti-reflection surface layer facing the first substrate.
4. The liquid crystal display device as claimed in claim 3, wherein the anti-reflection surface layer is made of refractory metal.
5. The liquid crystal display device as claimed in claim 4, wherein the refractory metal comprises a metal selected from the group consisting of Cr, Ta, Mo, and Ti.
6. The liquid crystal display device as claimed in claim 3, wherein the anti-reflection surface layer is an oxidized metal film.
7. The liquid crystal display device as claimed in claim 1, wherein the light-cured sealant is a UV cured sealant.
8. The liquid crystal display device as claimed in claim 1, wherein the light-shielding matrix is a black matrix.
9. The liquid crystal display device as claimed in claim 1, wherein the liquid crystal display device is a normally black mode liquid crystal display device comprising a pair of polarizers attached on the first and the second substrates respectively in a manner that the polarizers on the first and the second substrates cover areas on the first and the second substrates facing the slit.
10. The liquid crystal display device as claimed in claim 9, wherein the liquid crystal layer comprises a vertically aligned liquid crystal having a negative dielectric constant anisotropy, and the polarization axes of the pair of polarizers are perpendicular to each other.
11. The liquid crystal display device as claimed in claim 9, wherein the liquid crystal layer comprises a horizontally 90 degree twisted nematic liquid crystal having a positive dielectric constant anisotropy, and the polarization axes of the pair of polarizers are parallel to each other.
5263888 | November 23, 1993 | Ishihara et al. |
5724107 | March 3, 1998 | Nishikawa et al. |
5877831 | March 2, 1999 | Leenhouts et al. |
6268896 | July 31, 2001 | Takasaki et al. |
6424394 | July 23, 2002 | Morii |
20010007487 | July 12, 2001 | Yoon et al. |
20020047963 | April 25, 2002 | Youn et al. |
Type: Grant
Filed: Dec 6, 2002
Date of Patent: Mar 28, 2006
Patent Publication Number: 20040017526
Assignee: Chi Mei Optoelectronics Corp. (Tainan)
Inventor: Chen Lung Kuo (Tainan)
Primary Examiner: Dung T. Nguyen
Assistant Examiner: Thoi V. Duong
Attorney: Finnegan, Henderson, Farabow, Garrett & Dunner, L.L.P.
Application Number: 10/310,860
International Classification: G02F 1/1333 (20060101);